Numerical investigation of tunnelling effects on existing piles in structured clay

Abstract

Tunnel construction may induce ground deformations and affect the adjacent pile foundations. Up to now, few studies have investigated the soil-tunnel-pile interaction in structured clay. In this study, an anisotropic structured clay model is implemented in the finite-difference code FLAC^3D to investigate the effects of tunnelling on existing piles in structured clay. The model is first calibrated based on the oedometer and undrained triaxial tests for Shanghai structured clay. Then the numerical model and the modelling procedure are introduced and validated by simulating the centrifuge model tests of tunnelling adjacent to piles in remoulded kaolin clay. Thereafter, influences of clay anisotropy and structure on the existing piles due to tunnelling are investigated using the calibrated parameters for Shanghai structured clay. It is observed that the influence of clay structure on the shape of the deflection and bending moment of the pile is not significant. However, the introduction of the anisotropy and the adhesive mean stress may reduce the ground settlement while increasing the lateral soil movement at the tunnel axis depth, whereas the introduction of the bonding ratio may have the opposite effect. Moreover, introducing both the anisotropy and the soil structure will lead to the increase of pile moment.

Keywords:

• Tunnelling
• pile
• clay
• soil structure
• finite difference method
• bounding surface model

Acknowledgments

This research was financially supported by the Scientific Research Project of Anhui Provincial Education Department (Grant No. KJ2021ZD0066); the National Natural Science Foundation of China (Grant Nos. 51608005 and 51579179); and the RIF project (Grant No. R5037-18F) from the Research Grants Council (RGC) of Hong Kong Special Administrative Region Government (HKSARG) of China.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.